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Author: Brett Little

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GHI Education Manager

My experience with wildfire smoke: Impact on indoor air quality and solar power

Recently, in mid-July 2026, Canadian wildfire smoke entered Michigan, resulting in the worst air quality I can recall in my lifetime.  For two days, we sat in the hazardous range listed within the EPA AQI rating. Everything was foggy, like a normal heavy-fog day, but the air outside tasted like metal and smelled like a distant wood fire, but not the pleasant kind. In addition, we had just come off a heatwave that week, and some of the days were fairly hot during the smoke event.
 

I had no interest in doing this or writing this, as I do not take pleasure in it. Still, I decided to take advantage of the bad situation and to run indoor air quality experiments to see how outdoor air was affecting my indoor air quality and solar power output.

 
My first action Wednesday night when the smoke started to descend into Michigan was to shut down my Energy Recovery Ventilator (ERV), think lungs for your house, a system that brings in fresh air and exhausts stale air. The reason I did this was the hazardous level of smoke coming in; I was worried that even my robust MERV 13 filter on the ERV and MERV 16 filter would not filter out the additional pollution a wildfire brings beyond particulate matter like Pm2.5 and PM10.
 
By shutting down my ERV, I was making a conscious trade-off: I knew I may increase
Airthings monitor in hallway near thermostat showing CO2 spikes
household CO2, certainly, and maybe to a minor extent indoor VOCs and humidity, but the trade-off was not letting the nasty wildfire pollution into my home.  In addition, I set my heat pump filter (same as your furnace/AC filter) to high recirculation mode because it is a MERV 16 filter designed to filter out wildfire smoke that gets pulled into the house, even with the ERV off.
 
Now, while I do not have an outdoor air quality monitor to know exactly the air quality directly at my house, I do have several indoor air quality monitors, so I have tracked my air quality before, during, and after this event.
 
One of the first things I noticed on the first major smoke day was that we used our local ventilation systems, such as a range hood to vent while we were cooking or a bath fan to vent while we were using the bathroom or taking showers.
 
The first spike on the left was from turning on the range hood to cook breakfast; the 2nd spike was from lunch made in the oven with the range hood on again; and the 3rd and 4th spikes were from running the bath fan during showers.
 
Spikes in PM2.5 from local ventilation on hazardous level (500 AQI) smoke day show on Awair air quality monitor inside
 
So basically, what’s concerning here is that one turns on their ventilation systems to remove pollution, but during extreme wildfire events, you’re actually bringing more pollution into the house. My home is about 978 CFM and/or four (4) air changes per hour, which is not the tightest home, but that’s what our current code is here in the State of Michigan. Other states and other green building programs are usually around that level as well.  But that’s enough leakage to worry about if you bring on an exhaust-only fan like a constantly running bath fan, which the vast majority of our homes, even newly built ones, and multifamily buildings are using as we speak. It’ll draw in that polluted air through the cracks and crevices in the home, and keep it in there. You will see some more examples of this below.
 
Now, one thing I didn’t get to experiment with was whether turning off my high-
efficiency filtration system in my heat pump would have caused my particulate pollution numbers to go up, since my home isn’t super airtight. This was because it was very hot out, and so I had to keep my heat pump cooling my house, which meant the filter was running as it should be, so the only way to experiment with that would’ve been to turn off my heat pump and suffer through heat just to see how my house handles smoke without any mechanical systems running. Certainly, if we have a hazardous wildfire event in one of the swing seasons, when I don’t need to be heating or cooling, I could test that out and update.
 
Speaking of a wish list of things to test, as the hazardous smoke wound down, someone on LinkedIn told me they decided to switch their ERV system to positive pressure to help keep the smoke from entering the home by pushing the air out the natural leaks in all homes and then using their MERV 13 to filter the incoming air. I wish I had tested this more during the hazardous smoke, but I did switch over to this by moving the exhaust dial to 70 CFM and maintaining 100 CFM on the intake during the next few days when we spent most of the time in the EPA IQA unhealthy and very unhealthy range, and it seemed at least effective there.  
 
Now, that being said, our Green realtor friend Wayne, who works in the Chicagoland area, shared an update of his house using his air quality monitor on LinkedIn during the event. He told me he wasn’t home at the time, and his energy recovery ventilation

 system was running and drawing in the outdoor air through a MERV 7 filter and only being filtered through the standard low MERV heat pump conditioning system, so you can see from his post that his house quickly became polluted until he shut the system down the numbers went down from the red to yellow and so they were still elevated in higher threshold above what people should be consistently exposed to. He also shared that his house is pretty tight, around 1 air change per hour, showing even in tighter homes some pollution was coming in and it was not being cleaned by a MERV 7 filter system.
 
Now how does a more advanced Passive House fare? Dale Hulst, who recently built MINet0-1, got to experiment with this as he currently has his home listed on the market but has it monitored.

 “The big smoke event was a great test of the house. It performed well, but not as well as I’d hoped given my MERV16  final filter on the Energy Recovery Ventilator. I decided to upgrade the recirculation plenum filter (the system with three duct fans that I added late in the game). I upgraded from MERV 11 to MERV 13, toward the end of the smoke event, on July 20 in the afternoon, and thought I saw improvement, but it was hard to know for sure as the outdoor air was significantly cleaner by that time.  We’re likely to see some bad 300+ AQI days again, which will be

 a better test.” – Dale Hulst.

Dale also shared with me that this particular Energy Recovery Ventilator has a MERV 13 intake filter ahead of the MERV16 final filter which also includes carbon for removing VOCs from the incoming fresh air.

 
 
“My goal is to show the new buyers / owners they can safely run the ERV in a wildfire event. With the fresh filters and upgraded MERV13 in the recirc system, I’d like to think I could run it. Some of the PM2.5 in the house may have been from the little bit of infiltration that gets into the house through the doors, etc.  (0.03 CFM/FT2 at 50 pascals per final blower door test). If the ERV is taking out everything intentionally being brought in, my hope is the recirc filter will take out whatever is unintentionally leaking in.”- Dale Hulst.
 
 
 
So just going on beyond a couple anecdotal examples here with myself, Wayne and Dale, where I grow really concerned is when I look back over the last 15 years I’ve been providing consultations to help people at where I have just helped people achieve our building code in Michigan, which is four air changes per hour (4 ACH) and typically includes running a negative pressure bath fan to meet the ventilation standards, which are typically referred to ASHRAE 62.2.
 
Beyond that even the Green Building Certification programs we help consultant on such as LEED or Green Communities are fairly similar at the lower levels where typically people are just at a bare minimum meeting somewhere between two and four air changes per hour in their home or multifamily units, then having a bath fan run to meet the basic ventilation standards such as ASHRAE 62.2 2010 or maybe 2016 and then putting in a MERV8 filter in the HVAC system.
 
In all these cases and all these homes that are otherwise designated to meet a new building code or even a green standard, one can infer that people went into their houses thinking they were protecting themselves from the wildfire but heavy smoke at these levels are shown here above with their bath fan that is running and would’ve been otherwise used to keep their air healthy in their house was instead pulling in the wildfire smoke, and the MERV 8 in their HVAC system filter wasn’t enough to filter it but only spread it around. Maybe some of these people were savvy enough to notice and shut down their bath fans, install HEPA filters, or build a DIY Corsi–Rosenthal Box fan at some point, but that likely is not the case for most people who are not thinking about these things.
 
My main point is that, unfortunately, our current codes and Green Building standards are not protecting us against this new threat, which was probably unforeseen here in the Midwest and Northeast.
 
I would argue this is an opportunity to reflect on and review our building codes. Look at our Green building programs and significantly increase their requirements while providing the resources available for home renovations in new construction to achieve these outcomes.
 
The good news is that, even if, let’s say, wildfire smoke rarely came again or ever came again, the benefits of making our homes wildfire smoke-resistant would extend beyond just keeping smoke out to include improved home health, comfort, and energy cost savings.
 
So what do we need to do?
  1. Airseal, airseal and then airseal again, ideally to Passive House levels
  2. Boost HVAC filtration to MERV 13-16 (but be warned if you do!)
  3. Get Smart; systems need to know air quality and respond to smoke events
  4. Change policy/programs

First and most important, we need to air-seal our homes and reduce leaks, ideally aiming for Passive House standards to the best of our abilities. This can be done easily on new construction, but once the home is built, it gets harder and harder depending on its condition, unless there’s a gut renovation.  Beyond keeping smoke out during extreme events, we also have humidity control, which reduces winter dryness and summer/swing-season mold/allergy issues, reduces energy loss, and could lead to improved comfort, especially during extreme heat or cold. Also, in many areas with air leaks, pests can enter the home, and water can get in those areas as well, so targeting air leakage has multiple benefits beyond just smoke.

Next, we need to boost the filtration capacity of our ventilation, heating, and cooling systems. The problem with doing this, though, is that the heavier the filtration is, the more drag it puts on the system’s efficiency due to something called static pressure. With new construction, this can be easily addressed through Manual D, where you properly design the ductwork and include a 4- to 5-inch filter with MERV 16 as part of the total system design and proper install. Then the HVAC is properly commissioned to verify that the installation works and the system is performing. Some HVAC systems even self-commission and can report issues during operations.

For existing homes, this becomes a lot more complicated because in many cases you are stuck with the ductwork you have, as it can be very expensive to get to tearing out drywall, tearing out walls, and tearing out and replacing ductwork; rarely do any of the energy efficiency programs or weatherization pay for this work but getting a good HVAC contractor assess the existing system for performance is still important and improvements can be paid or funded through some programs. You would have someone review the ductwork during a GreenHome Inspection, maybe do duct blaster testing or pressure pan testing to see how leaky it is, and check to see if ducts are panned in the joists. Then, check the length and size of the ductwork, and have the HVAC contractor or assessor complete a static pressure test on the existing system to see what its current pressure is. From there, a plan can be put together that is specific to each property to determine if it’s possible to update to at least a MERV 13 filter, which is what is needed to start filtering out wildfire smoke, or even a MERV 16 without dragging down the static pressure and reducing the life and efficiency of the system. Each home is going to be on a case-by-case basis, depending on the situation, budget, and the homeowner’s or building owner’s desires. If a home is using ductless air source heatpumps (aka mini-splits)  to heat and cool, or radiant, you might have to try to do the filtration through the ventilation system instead.
Now for ventilation systems, these are usually a detriment to health and extreme wildfire smoke, but the first thing we need to do is make sure they have thick filters in them and are also designed appropriately with good static pressure without major bends or kinks in the ductwork and lots of 90° or sharper turns. I haven’t seen too many ventilation systems with MERV 16 on them other than Dale’s noted above, but I know many like what I have; the Panasonic Intellibalance one has at least a 13 on it, which helps. But more than this, we need smart ventilation and demand-controlled systems that can automatically: sense bad air, shut down, and recirculate, as most people aren’t thinking about these kinds of things on a daily basis and want to rely on the system to ensure their safety before it is too late. This would mean that the ventilation system is communicating with an outdoor air quality monitor on the house, in the area, or, if necessary, with the general EPA outdoor air quality data. Then the system would also monitor indoor air quality and either shut down the intake based on how bad it gets outside and what’s being sent inside, or maybe even throttle it back. Hence, it was a balance between some ventilation and reducing higher levels of particulates in the house. But as I said, if you’re relying on your ventilation system to filter the air because your HVAC is older and can’t have the updated filter, or you’re using mini-splits or radiant heating and cooling, then you’ll want to rely on your ventilation system to shut down, but still provide filtration for the home, and I’ve never seen any system do that short of a Build Equinox CERV unit which has the ability to detect the outdoor water wildfire smoke and do just that shut down from being a ventilation system to just a filter system which then we’ll filter the air in the home only for any of the wildfire smoke that migrate in through the cracks and crevices.  
 

To be fair, this can all be expensive, so in the short term, what we highly recommend is a low-cost air quality monitor that can review particulates, and then a DIY filter fan that you can build a couple and set up in a room during emergencies.

But moving forward, I think it’s imperative that our codes and green building programs change, as well as our incentive structures, to help fund these kinds of advanced upgrades during Home retrofits, or especially during new construction, where it’s a lot easier to take care of.

The good news, too, is more and more people may be willing to pay for these upgrades; a recent Redfin report shows 36% of buyers value a clean air home over other luxuries. 

 

What about solar power?

So I promised to talk about solar power. Certainly less of a worry because the majority of people don’t have solar power, but we all breathe; if you do, or you’re considering it, wildfire smoke is going to be a detriment to solar power output just the same.

Solar before smoke on a typical July day

Now, thankfully, I had one really nice full sunny day right before the wildfire smoke event, and then during one of the most hazardous days, the weather told me, at least according to the weather, I couldn’t see because of all the smoke that it was truly a full sunny day without any clouds. But otherwise, most of the smoky days we had also had clouds, so that skewed some of the data, but if you look at the sunny day right before the event and the sunny day during the event here, you’ll see all in all we had a 17 kW decrease in solar

 percent again from extremely rare hazardous smoke output or otherwise a 27%

change.

This similair % drop is confirmed by Dale Hulst of MINet0, who also confirmed his solar data with me; you can see on average his home peaks at 70 kW and on the smokiest yet sunniest day (same as mine) he dropped to 50 kW, so 28%, pretty close and his system is a bit bigger and all south facing so of course the bigger they are, the harder they fall or state larger systems will see larger % drops.

So overall, unfortunately, as more wildfire smoke is forecasted to occur. we will also lose energy output with solar power, ironically, as solar is meant to reduce carbon emissions and help prevent climate change, which worsens wildfire smoke in forest fires. The good news is, despite the smoke output, I still was able to stay off grid most of the day and most of the peak energy usage time, and the other good news is the smoke will depress the heat from the sun, which is another thing that diminishes solar panels: extra heat.

If you want to see more details about my home, the monitors, systems I use, etc as well as a CEU tour of my house, go to https://greenhomeinstitute.org/greenstar_homes/little-residence-pearl-platinum-aiming-for-greenstar-zero-carbon/

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The Resilient Home: Building Materials and Best Practices for Reduced Mold Risk

The Resilient Home: Building Materials and Best Practices for Reduced Mold Risk

By: Grace Waters, Senior Editor, Environment Co

Mold prevention starts long before a building is occupied. It begins with choosing the right materials, managing moisture effectively and following construction practices that keep water out. While mold spores are naturally present in the air, they only grow when moisture is available. As such, designing with moisture control in mind is the key to creating healthy, durable and resilient buildings.

1. Moisture Control as the Foundation of Mold Prevention

The most effective mold prevention strategy is to control moisture before it accumulates within building assemblies. Water can come from rain, plumbing leaks, high indoor humidity or condensation, so moisture management should be a priority during design and construction.

 

Building envelopes should prioritize continuous water-resistive barriers, properly integrated flashing, effective drainage planes and airtight construction. These components work together to direct water away from vulnerable assemblies while minimizing uncontrolled air leaks that can transport moisture into wall cavities.

 

Proper site grading also helps with moisture management. Directing surface water away from foundations, incorporating appropriate drainage systems and preventing standing water around the building perimeter reduces the likelihood of long-term moisture infiltration.

2. Selecting Mold-Resistant Building Materials

Mold can begin growing within just 24 to 48 hours while producing allergens and irritants that impact health. While no material is entirely “mold-proof,” many modern construction products are designed to minimize moisture absorption and discourage microbial colonization.

Fiberglass-Faced Gypsum Board

Fiberglass-faced gypsum board has become an increasingly preferred alternative to traditional paper-faced drywall in moisture-prone spaces. Because fiberglass facers contain little organic material, they provide fewer nutrients for mold growth while maintaining similar structural performance.

Cement Board

Cement board remains a reliable substrate for bathrooms, kitchens, laundry rooms and other high-moisture environments. Unlike gypsum-based products, cementitious boards resist deterioration during repeated wetting cycles. Alternatively, fiber-reinforced concrete and other renewable or recycled substrates can be used to reduce emissions by up to 40% by 2050.

Moisture-Resistant Insulation

Engineered insulation materials also contribute to mold resistance. Closed-cell spray polyurethane foam, rigid foam insulation and mineral wool provide low moisture absorption while helping maintain consistent interior surface temperatures. By reducing thermal bridging and minimizing the potential for condensation, these materials strengthen the building’s overall resistance to mold.

Durable Exterior Cladding

Exterior cladding systems should be selected for both durability and moisture management. Masonry, metal panels and properly detailed rainscreen assemblies promote drainage and drying while reducing prolonged moisture exposure behind exterior finishes.

Mold-Resistant Flooring

Concrete, ceramic tile, natural stone and moisture-resistant vinyl products generally outperform carpeting and untreated wood in areas susceptible to elevated humidity or occasional water exposure.

3. Design for Drying

Keeping moisture out is important, but buildings should also be designed to dry out if water gets in. Instead of trapping moisture inside walls, modern building designs allow it to escape while preventing excessive buildup.

 

Features like ventilated rainscreen systems create an air gap behind exterior cladding, helping water drain away and allowing walls to dry naturally. Proper roof and attic ventilation also helps reduce condensation, protects roofing materials and lowers the risk of mold developing over time.

4. Control Indoor Humidity

Good ventilation is essential for preventing mold, even in well-built homes. Whole-home ventilation systems, like ERVs, reduce moisture compared to supply-only ventilation, and ventilating dehumidifiers bring in fresh air while helping control indoor moisture.

Bathrooms, kitchens and laundry rooms should also have exhaust fans that vent directly outside to remove excess humidity. Keeping indoor humidity between 30% and 50% helps prevent mold growth while improving comfort and protecting building materials.

5. Reducing Future Mold Risk

Using mold-resistant materials is only part of the solution. Proper installation and quality construction are just as important for preventing moisture problems.

Keep Materials Dry During Construction

Building materials should be protected from rain and allowed to dry before walls and ceilings are closed up. Using moisture meters to check lumber and sheathing can help ensure they are dry enough before insulation and finishes are installed.

Seal Common Leak Points

Areas around windows, doors, roofs, plumbing and foundations are especially vulnerable to water intrusion. Proper flashing, sealants and waterproofing help keep moisture from getting trapped inside the building.

For example, proper chimney flashing and waterproofing prevent rain from entering surrounding roof assemblies, reducing the risk of moisture damage and mold growth. Ensuring proper waterproofing helps protect the structure around a chimney from moisture damage while reducing the risk of toxic gas exposure and undesirable odors. Consider adding in heatpumps and sealed combustion appliances like water heaters and furnaces to then allow the removal of the chimney entirely during the roofing project. 

Inspect Before Closing Walls

Regular inspections during construction can catch moisture issues or installation errors before they are hidden behind finished walls. Addressing problems early is far less costly than repairing mold damage after the building is complete.

Building for Long-Term Performance

Creating a mold-resistant home requires more than selecting specialized products. It needs an integrated design philosophy that considers moisture control throughout every stage of planning, construction and material specification. Effective drainage, continuous air barriers, humidity management, proper ventilation and durable moisture-resistant materials all contribute to a building capable of maintaining healthy indoor conditions for decades.

As such, prioritizing these principles transforms mold prevention from a reactive maintenance concern into a proactive design strategy. The result is a resilient home that supports structural durability, occupant well-being and sustainable performance throughout its entire life cycle.

 

 

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The Hidden Impact of AC Maintenance on Home Embodied Carbon

Most conversations about a home’s carbon footprint focus on operational energy, such as the electricity an air conditioner draws while it runs. Embodied carbon typically receives far less attention. 

 

Not understanding the emissions associated with manufacturing, transporting, installing and replacing an AC system can create great blind spots. When energy and material consumption are taken into account, the embodied carbon of AC equipment can rival the amount of carbon it releases over years of actual operation.

Why AC Equipment Carries So Much Embodied Carbon

An AC system is an assembly of many components, such as compressors, condenser coils, refrigerant lines, fans and ductwork. These components carry their own upstream emissions from mining and fabrication, as well as material costs for manufacturing. Refrigerant production adds another layer, since many refrigerants used in such systems have a high global warming potential if they leak. 

 

None of this shows up on a utility bill, which is part of why it’s so easy to overlook. A homeowner comparing two AC units based solely on their energy efficiency ratings is only seeing half the environmental picture.

How Maintenance and Replacement Add Up

Replacing components has its own embodied-carbon cost each time, since every replacement part was manufactured somewhere before it arrives at a home. A system patched together with frequent part replacements over its lifespan can end up carrying more cumulative embodied carbon than one properly sized and maintained from the start. This is simply because more manufactured components are cycled through. 

 

Full replacement carries an even larger embodied carbon hit, and it’s also where timing plays a notable role. An aging unit approaching the end of its service life is often better replaced than repeatedly patched. This is because continued part-by-part repairs on a failing system can consume more material and cause more disruption than a single, well-planned replacement with a properly sized unit. 

 

Refrigerant handling during maintenance deserves particular attention. Servicing an AC system involves opening refrigerant lines, and improperly handled service work can release refrigerant into the atmosphere — a direct emissions event separate from the embodied carbon of manufacturing. Proper recovery and recharging prevent refrigerant from being vented during a service call. This matters because refrigerant leaks create climate impact regardless of how efficiently the AC unit runs day to day.

Designing Homes That Need Less From Their AC

The most effective way to reduce an AC system’s lifetime embodied carbon is to decrease how hard it has to work in the first place. Much of this comes down to the building itself rather than the equipment. 

 

Poor insulation is one of the most common culprits behind an underperforming AC system. A home that isn’t properly insulated allows unwanted heat gain regardless of how well the equipment itself is running, which is one of several factors, including excess indoor humidity or an aging system, that reduce an AC system’s cooling power.

 

Improving insulation, sealing air leaks, and adding shade through window placement, overhangs or landscaping all reduce the cooling load a home places on its AC system. These solutions reduce operational energy use and the frequency of maintenance and premature replacement.

 

Passive design strategies extend this further. For example, using cross-ventilation to move heat out naturally reduces reliance on mechanical cooling. Homeowners can also consider orienting a home to limit direct afternoon sun exposure. While none of these strategies eliminates the need for an AC system in most climates, each one reduces the runtime and strain on the installed equipment, extending its usable life and delaying the embodied-carbon cost of eventual replacement.

What to Look for When Equipment Is Unavoidable

An AC system is still necessary in many climates, but a few equipment choices can meaningfully reduce lifetime carbon impact. Right-sizing a unit to a home’s actual cooling load reduces wear from constant short-cycling and extends the equipment’s realistic lifespan. 

 

Furthermore, systems that use lower-global-warming-potential refrigerants reduce the impact of future leaks during servicing. Equipment with a high efficiency rating and a strong track record of parts availability also makes long-term maintenance easier, since it keeps a unit in good working order longer rather than pushing it toward premature replacement. 

 

Adopting a direct approach to reducing emissions is typically more beneficial to the environment than carbon offsets, which often take an indirect approach to tackling core emissions issues. 

Rethinking What Efficiency Means

An AC system’s environmental footprint extends far beyond its operational use. Every replacement part and service call involving refrigerant carries its own embodied carbon, and that carbon adds up over a home’s lifetime in ways that operational efficiency ratings don’t capture. By treating equipment longevity and building design as part of the sustainability equation, homeowners can have a much more complete picture of what it actually costs to keep their living space cool. 

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Cost Savings When Going All Electric for GHI Members

Interested in going all-electric at home or on a client’s project?

GHI members now get $100.00 off these systems to help increase electrification.

Many homeowners are told they need $5,000+ panel upgrades before installing EV chargers, heat pumps, or solar.

The existing panel often has enough power. Stepwise just manages it smarter.

Learn more about electric panel management and how it works in this detailed article and video


To access the discount, GHI members go to your membership benefits page. Not a member? Become a member today and get access. 

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Residential Solar Incentives and Rebates Every Builder Should Know

Residential Solar Incentives and Rebates Every Builder Should Know

 

By: Grace Waters, Senior Editor, Environment Co

Solar power is getting more affordable and effective, making it one of the most premium ways to generate electricity. Construction professionals need to remind residential and commercial clients of the opportunities available for further cost savings, ranging from local to federal incentives, including tax credits and rebates. These are some of the options experts need to keep in mind when helping their communities install solar and achieve financial and carbon savings.

Federal Solar Investment Tax Credit (ITC)

The Federal ITC for solar has changed since the OBBBA took effect in 2025. While this altered the benefits taxpayers received, it is still possible to benefit from solar technology. To be eligible, the residential or commercial solar facility must begin construction by July 4, 2026, and must be in service by December 31, 2027.

 

The credit deducts 30% of the investment expenses from federal income taxes. If the project is an affordable multifamily home, it will be eligible for further reductions. Claim the credit by filing IRS Form 5695 with a federal tax return, providing information about the cost of the system when submitting. This will verify when it was built and when it became active.

 

In 2026, Warren Woods Public Schools in Michigan demonstrated the value of the ITC. It installed 300 kilowatts of roof-mounted solar on a new roof. The 40% credit cut the total costs of the project by $735,836, powering all of its offices, labs and athletic facilities. While this was under a previous version of the ITC, it is subject to change, while still providing aid for projects.

California’s Self-Generation Incentive Program (SGIP)

California’s push to reduce energy emissions is notable, especially with efforts like the SGIP. It encourages citizens to install backup energy systems, combined solar and energy storage, and more. This helps Californians obtain energy independence, resilience and redundancy. If a household or business installs solar panels, they may delay installing energy storage due to the up-front cost. Programs like this soften this decision.

 

To obtain the rebates, applicants must review the SGIP Handbook, which details what they must do with the funds. They have one year to use them and enroll in a Demand Response Program. Customers of these eligible utility providers may apply by speaking to their provider:

 

  • Pacific Gas and Electric
  • Southern California Edison
  • Los Angeles Department of Water and Power
  • San Diego Gas and Electric
  • Southern California Gas Company

 

Applicants will receive generous assistance even for low-income residential properties, which promotes environmental justice and equity.

Energy-Efficient Commercial Buildings Deduction (179D)

This is a federal program exclusively for business buildings. It provides deductions for energy-efficient structures that implement renewable energy for eligibility, with solar being one of the best options. It applies to buildings in service before January 1, 2027. The building must demonstrate a 25% or greater reduction in power costs and energy use compared to the reference in the requirements. It can achieve this by:

 

  • Installing solar
  • Updating HVAC systems
  • Reinforcing the envelope
  • Using energy-efficient lighting

 

This covers more than renewable energy, but it helps corporations justify the expense by bundling it into other energy-saving initiatives. This is also claimed on federal income taxes, provided the building is certified by the Illuminating Engineering Society of North America and the American Society of Heating, Refrigerating, and Air Conditioning Engineers’ standards.

 

Leveraging this tax credit will promote greater energy security, especially in places prone to severe weather and natural disasters. States like Georgia may receive 50 inches of rainfall yearly, so residents need well-insulated and resilient buildings to resist structural damage and temperature extremes.

New Jersey’s Successor Solar Incentive (SuSI) Program

Another well-known, state-specific program is New Jersey’s SuSI, which includes many smaller initiatives that pay homeowners and companies for the energy they generate. They reimburse the community with Solar Renewable Energy Certificates (SRECs) and other benefits. Some of the currently active options include:

 

  • Administratively Determined Incentive Program: Incentives for net metering and community solar projects of five megawatts or less
  • Competitive Solicitation Incentive Program: Aid for grid-supply solar systems with capacities of more than five megawatts
  • Community Solar Energy Program: Help for community-focused generation projects
  • Community Solar for Subscribers: Assistance for customers connected to conventional utilities that integrate solar into their generation
  • Remote Net Metering: Rewards and approves remote net metering projects for public entities

 

Eligibility for each program is available, though customers need to register their system with the SuSI Program to start receiving payments.

Shining Returns on Investment

Construction professionals must dive into their local, state and federal offerings to help customers justify solar installations. It is one of the most critical recommendations they can make, especially as energy resilience and financial security are top of mind for residential and commercial clients alike.

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Net-Zero Home Electrical Systems: Smart Management and Safety for Solar Plus Battery Integration

Rising energy costs and unpredictable grid outages are pushing North American residents toward efficient home electrical systems that combine solar panels, battery storage and intelligent controls. These systems deliver energy independence beyond basic backup power, but success depends on integration, not just hardware. When properly managed, they provide stable costs, outage protection and savings traditional grid connections cannot match.

What Defines a Modern Net-Zero Home?

A modern net-zero home achieves enough efficiency to produce as much power as it consumes each year. This performance standard sets the benchmark for residential construction in North America.

Understanding the Goal of Energy Independence

Energy independence transforms the homeowner’s relationship with the utility grid. Instead of relying entirely on external power, the household generates its own electricity and stores surplus for later use. This shift insulates residents from service interruptions and keeps essential functions running during grid failures, while providing stable monthly costs tied to consumption rather than fluctuating utility rates.

Core Benefits for Homeowners and the Grid

Lower utility bills offer the most immediate advantage, and property values climb as efficient homes become more desirable in competitive markets. Homeowners pursuing net-zero construction can qualify for the 45L Tax Credit by ensuring their properties meet program eligibility requirements from the U.S. Department of Energy’s Efficient New Homes Program, which helps offset initial investment costs.

 

Research demonstrates that 40% to 60% adoption of these distributed resources delivers optimal financial, environmental and resilience outcomes for communities.

 

Residential renewable installations create broader benefits beyond individual savings. These systems generate jobs, strengthen community resilience against outages and reduce reliance on fossil fuels across diverse income levels.

Key Components of an Integrated Home Electrical System

Three components form a net-zero system:

 

  1. Solar panels convert sunlight into electricity.
  2. Battery storage holds excess power for evenings and cloudy periods.
  3. The electrical panel directs flow between the array, batteries, home circuits and grid connection.

 

These parts communicate continuously to optimize usage. When solar production exceeds household demand, the surplus charges batteries. Full batteries send remaining excess to the grid. When solar generation falls short, the system draws from battery reserves first, then taps grid power only as needed.

Smart Energy Management in Solar Power Systems for Homes

Modern net-zero installations do more than generate and store power. Management platforms analyze consumption patterns in real time, learning household routines and making automatic adjustments to maximize efficiency. The software can delay nonessential appliance cycles until peak solar hours and prioritize battery charging based on incoming weather forecasts.

Using Smart Thermostats for Efficient Climate Control

Smart thermostats offer the simplest entry point into whole-home optimization. Programmable models let occupants set temperature schedules that match when people are actually home. Advanced systems connect to smartphone apps so residents can adjust climate settings remotely before they arrive.

 

The real value shows up when the thermostats coordinate with solar production schedules. Shifting cooling or heating loads to times when panels are generating surplus electricity lets the system reduce the home’s grid power draw during peak demand periods.

A Real-World Example of Integrated Design

Ball State University’s “Alley House” demonstrates how these principles translate into practice. The residence combines R-40 walls and R-92 roof insulation with triple-glazed windows and rainwater collection systems, while its solar photovoltaic array can generate a net-positive energy balance annually. This allows it to produce more electricity than the home consumes.

 

Ball State took top honors in the U.S. Department of Energy’s Solar Decathlon Build Challenge in 2023, proving net-zero performance works with current technology and thoughtful design.

How to Monitor and Maintain the System for Peak Performance

Modern applications provide real-time visibility into energy flow, showing what the panels are producing, how charged the batteries are and how much power the home is drawing from the grid. Under optimal conditions, monocrystalline panels can achieve 27% efficiency, making performance tracking especially valuable for spotting when output drops below expectations.

 

Third-party platforms simplify this process by letting homeowners track inverters, meters and sensors through a single interface. These tools consolidate reporting and deliver standardized alerts regardless of what specific hardware is installed locally.

Essential Safety Codes and Installation Standards

National and local electrical codes establish minimum requirements to protect occupants and ensure that equipment functions as designed. The National Electrical Code (NEC) sets the foundational safety rules for all electrical work across the United States, with specific articles governing solar installations and battery storage systems. These cover everything from conductor sizing to protective device specifications.

 

NEC Sections 690.7 and 690.8 require installers to correctly size conductors and protective devices. Getting these specifications right prevents overheating, reduces fire risk and ensures the system can handle maximum current loads without failure.

Why Professional Installation Is Nonnegotiable

Complex codes and electrical hazards require professional installation, which is why choosing the right contractor represents the most critical decision. It is important to ask installers about the following:

 

  • Battery placement and code compliance: Installers should explain the proposed location, code reasons for that choice and backup options if permitting fails.
  • Permit responsibility: Contractors should clarify who pulls permits, whether fees are included and what happens if changes are required.
  • Electrical upgrade scope: The quote should state whether panel upgrades or load management hardware are included or could trigger additional costs.
  • Post-installation support: Installers should specify who handles faults and what response times apply.

Building a More Resilient and Future-Proof Household

Net-zero home systems deliver benefits that extend well beyond lower utility bills. The right system protects against grid failures and rate increases while cutting environmental impact. Homeowners ready to make the transition should work with certified professionals who know local codes, climate factors and current incentive programs.

Categories
Guest Articles

The Hidden Energy Costs of Dirty Ductwork – And How Smart Design Prevents It

As North America continues to embrace green building practices, homeowners and construction professionals are paying closer attention to every component that affects energy efficiency. For green home builders, renovators and HVAC professionals, understanding the relationship between ductwork design and energy efficiency is essential. A well-designed duct system improves air quality and comfort and contributes significantly to long-term energy savings.

The Hidden Cost of Dirty Ductwork

Dirty, poorly designed or leaking air ducts can quietly undermine a home’s energy performance, increase utility costs and reduce indoor comfort. Air ducts serve as the delivery network for conditioned air throughout a home. When airflow is restricted, fans and blowers consume more electricity to maintain the desired temperature. 

 

In addition, clogged ducts can contribute to uneven heating and cooling, causing occupants to adjust thermostats more frequently and increasing overall energy consumption. In fact, ducts alone can account for 20% to 30% of conditioned air loss before it even reaches occupied spaces.

 

Over time, dust, debris, pet hair, construction particles and other contaminants can accumulate inside the duct system. While these contaminants may seem harmless, they can create airflow restrictions that force HVAC equipment to work harder than necessary.

 

Blocked ducts also strain the HVAC system, causing its components, such as fans and compressors, to wear out more quickly. This drives up repair costs and shortens a system’s lifespan, leading to costly replacements.

How Often to Clean Air Ducts

Even the most efficient duct system requires regular maintenance to sustain performance over time. Dust accumulation, pest intrusion and construction debris can gradually reduce airflow and can expose residents to airborne pollutants. The poor air quality can cause headaches, fatigue, respiratory irritation and allergies.

 

As such, recommendations vary depending on household conditions and cleaning performed as needed based on contamination levels. However, homes with pets, recent renovations, smokers or occupants with respiratory sensitivities may benefit from more frequent evaluations. Rather than adhering to a rigid cleaning schedule, it might be better to do condition-based assessments that focus on actual system performance and cleanliness.

Why Green Home Professionals Should Prioritize Duct Design

Builders and renovators are under increasing pressure to deliver measurable efficiency improvements. As such, ductwork presents one of the most cost-effective opportunities to achieve these goals, because many homeowners invest heavily in high-efficiency furnaces, heat pumps and smart thermostats while overlooking the distribution system responsible for delivering conditioned air. Without efficient ductwork, even the most advanced HVAC equipment cannot perform at its rated efficiency.

 

Lastly, for green building professionals, emphasizing duct design during project planning can provide a competitive advantage. It improves energy performance, enhances indoor air quality, lowers costs and provides greater comfort, all of which contribute to stronger project outcomes.

How Smart Home Design Starts with Efficient Air Distribution

Modern smart home design extends beyond connected devices and automated controls. It also involves creating building systems that work together efficiently from the start.

 

Ductwork should be treated as a core component of the home’s energy strategy. During new construction or major renovations, builders can implement several best practices to maximize duct performance.

Right-Sized Ductwork

Proper duct sizing prevents uneven heating or cooling by ensuring correct air velocity and pressure. Oversized ducts lower velocity and cause poor distribution, while undersized ducts restrict airflow, strain the blower and increase utility costs.

Shorter and Straighter Runs

Reducing unnecessary bends and minimizing duct length lowers airflow resistance. This allows HVAC systems to distribute air more efficiently while using less energy.

Sealed Connections

Air leaks at joints, seams and connections are common sources of energy loss. High-quality sealing methods help ensure that conditioned air reaches its intended destination rather than escaping into attics, crawl spaces or wall cavities. In fact, sealing ducts properly increases efficiency and lowers energy bills.

Strategic Duct Placement

Ducts are often located in uninsulated attics and crawl spaces where humidity can prematurely age the equipment and conditioned air can escape if the ducts are not air-sealed.

As such, ducts should be located within conditioned spaces to minimize the effects of duct leakage, as any conditioned air that escapes from the ducts enters the home’s conditioned areas.

Balanced Airflow

A balanced duct system promotes consistent temperatures throughout the home, reducing hot and cold spots that often require frequent thermostat adjustments and increased energy use.

From Hidden Losses to Measurable Savings

Dirty ductwork and poor duct design can create hidden energy losses that significantly reduce a home’s HVAC system efficiency. Airflow restrictions, leakage and improper layouts force equipment to work harder, increasing energy consumption and utility expenses.

 

Fortunately, these issues are preventable. Through smart home design principles such as proper sizing, sealed connections, balanced airflow and strategic duct placement, green homes can achieve substantial performance gains. Combined with regular inspections and appropriate maintenance, a well-designed ductwork system can deliver HVAC energy savings while improving comfort and indoor air quality.

Written by Jane Marsh Environment CO

Categories
Q&A Webinar After

Valuing, Financing High-Performance Green Homes & ADUs Article

Teresa Lopez, Green Energy Money (GEM), joined us recently for our  Weekly Wednesday Free CEU webinar Series.

If you missed this session, want to rewatch it, or want to share it with a friend or colleague, you can now do so, as the recording and an article on the topic are available below. 

What the session was about, according to our live attendees

The webinar highlighted the growing importance of having knowledgeable, specially trained appraisers for valuing green and high-performance homes, emphasizing that many traditional appraisers and realtors still lack understanding of these features. Attendees learned that requesting a green-certified appraiser is possible and critical for proper valuation, with the HERS rating standing out as the leading standard for assessing energy efficiency. The session also covered recent industry progress, such as Fannie Mae’s updated policies, new lending options, and improvements in recognizing green features in appraisals and MLS listings, while noting ongoing challenges like limited appraiser training and the need for better communication about the benefits of sustainable home features.

Please help us keep these webinars and writings going by becoming a supporting GHI member or by making a donation. 

Article Based on Webinar*

Abstract

This article explores the evolving landscape of green home financing, appraisal, and construction, focusing on market trends, valuation practices, and funding strategies for high-performance homes. Drawing exclusively on expert insights presented during the GreenHome Institute’s recent educational session, the discussion addresses challenges and opportunities for builders, contractors, housing professionals, and the general public. Topics covered include the integration of energy efficiency and resilience in new construction and retrofits, the role of appraisals and certifications, emerging financing products, and the knowledge gaps among industry stakeholders. Key takeaways are provided at the conclusion to summarize actionable points for professionals and consumers alike.

Financing and Valuing High-Performance Homes: Bridging the Gaps in Green Building

The residential green building sector continues to advance, driven by a combination of evolving building codes, growing consumer demand for energy-efficient and resilient homes, and a heightened awareness of sustainability in the housing market. Yet, despite significant progress in design strategies, product availability, and technical know-how, one of the most persistent barriers to widespread adoption remains the challenge of financing and accurately valuing high-performance homes. This article examines the current state of green home funding, appraisal practices, and construction trends, as well as the educational and systemic gaps that must be addressed to fully unlock the potential of sustainable housing.

Understanding the Market Gaps: Appraisal, Lending, and Education

A core obstacle facing the green building movement is the disconnect between the technical achievements of high-performance construction and the traditional mechanisms for property valuation and financing. Historically, appraisals have struggled to appropriately recognize the added value of energy efficiency, resilience, and other sustainable features. The market’s reliance on comparable sales (comps) often leaves out the data needed to establish the so-called “green premium”—the additional value associated with advanced building practices.

Recent updates are helping to close this gap. Notably, Fannie Mae’s adoption of the Uniform Appraisal Dataset (UAD) 3.6, which now incorporates Home Energy Rating System (HERS) scores and other performance measures, is a significant step toward more accurate valuation of green homes. Still, the standard reporting criteria on a national scale remain limited, and custom-built high-performance homes frequently do not appear in Multiple Listing Services (MLS), further hampering data collection.

The educational gap is equally critical. Builders, appraisers, underwriters, and real estate professionals often lack the training to identify, document, and value green features. While consumers—especially those in IT and engineering fields—are increasingly educated about these aspects, industry professionals must continue to bridge the knowledge divide to ensure that high-performance homes are properly valued and financed.

The Role of Building Codes and Certification

Building codes have become a major driver of change in the residential sector. In many regions, adherence to the 2024 code effectively positions builders as “green builders” by default, with HERS scores near 60 now aligning closely with code-built homes. High-performance homes that go further—such as those certified to Passive House standards or achieving HERS scores below 40—set new benchmarks for energy efficiency and resilience.

Third-party certifications play an essential role in supporting appraisals and financing. The HERS rating, in particular, is widely recognized for its ability to provide both predictive and verified energy savings. Other certifications, including ENERGY STAR, LEED, and the Department of Energy’s Home Energy Score for existing homes, also contribute to the valuation process. However, the ability of these certifications to influence appraisals depends on the appraiser’s training and the availability of supporting data.

Trends in High-Performance Housing: ADUs, Retrofits, and Resilience

Current market trends reflect both innovation and adaptation in response to changing consumer needs and policy environments. Accessory Dwelling Units (ADUs) have emerged as a powerful tool for increasing housing density, affordability, and multi-generational living. In states like California and Texas, relaxed zoning and building codes have enabled the proliferation of ADUs and small pocket communities, fostering both flexibility and attainability in the housing market.

The retrofit market represents a massive, untapped opportunity, with over half of America’s homes now more than fifty years old. Deferred maintenance is a pervasive issue, and the average energy-efficiency upgrade costs approximately $50,000. Regular maintenance and timely upgrades are essential not only for ongoing savings but also for preserving and enhancing property value.

Resilience is increasingly at the forefront of design and construction, with homeowners and builders prioritizing climate risk mitigation and durability. Integrated systems such as solar power, battery storage, and electric vehicle charging are becoming standard features in high-performance homes, offering operational cost savings and improved comfort.

Financing Mechanisms: Rebates, Mortgages, and Innovative Products

The complexity of green home financing arises from the need to balance higher upfront costs with long-term savings and value. Funding sources for high-performance projects are diverse, ranging from federal and state rebates—such as those provided under the Inflation Reduction Act—to utility incentive programs and specialized loans.

One of the most robust strategies for financing green projects is to leverage the mortgage process itself. By integrating the cost of energy-efficient improvements into the primary mortgage, buyers can take advantage of long-term, low-interest financing while simultaneously increasing the home’s value and reducing operational costs. New loan products, such as second-lien construction loans for ADUs and structured buy-downs (e.g., 3-2-1 programs), provide additional flexibility and make it easier for homeowners to invest in upgrades without sacrificing favorable rates on existing mortgages.

Reverse mortgages are another avenue for seniors with substantial home equity, enabling them to fund improvements or add ADUs for passive income without taking on new monthly payments. These options are particularly relevant as property tax and insurance costs continue to rise for older homeowners.

For builders and investors, recent guideline changes from Fannie Mae now allow up to five or six residential units under the same favorable terms as single-family homes, keeping projects out of the commercial lending sphere and making high-performance multifamily construction more attractive.

Appraisal Practices: The Importance of Data and Competency

Valuing green homes requires a nuanced approach that recognizes both tangible and intangible benefits. The UAD 3.6 mandates that appraisers identify specific green features and utilize mandatory certification reporting. However, the continued reliance on the sales comparison approach underscores the need for robust data collection and skilled interpretation.

The present value formula for energy savings enables appraisers to justify up to a 15% line-item adjustment for energy efficiency, but they must have access to accurate and relevant data. The appraiser’s competency is critical; homeowners and builders are entitled to request appraisers who are specifically trained to value green homes. Despite this, many lenders and appraisal management companies have yet to develop green appraisal panels or prioritize this expertise in their processes.

To address missing data in comps, appraisers can use the year built and corresponding building code as proxies for performance, connecting them to HERS or other rating systems. This approach helps quantify the difference between standard and high-performance homes even in the absence of direct sales comparisons.

Bridging the Educational Divide: Realtors, Appraisers, and Documentation

A significant knowledge gap persists in the resale market, where the high-performance features of a home are often lost or inadequately documented in real estate listings. Real estate professionals play a crucial role in ensuring that green attributes are communicated clearly and prominently, rather than buried in listing comments. Using precise language—such as “high performance” instead of “green”—can help distinguish homes that exceed current code and maximize their market value.

Data retention is equally important. Homeowners and builders should maintain comprehensive records of certifications, ratings, and upgrades, ensuring that the information is available at the time of resale or refinancing. Tools like Pearl Certification and municipal energy score programs (e.g., Portland’s mandatory Home Energy Score) are helping to standardize and disseminate this information, making it easier for appraisers and buyers to assess value.

Challenges and Opportunities in the Path Forward

Despite substantial progress, the green building sector remains a niche within the broader housing market. The absence of standardized, nationally recognized energy performance metrics complicates training and adaptation among appraisers and lenders. As building codes become more stringent and market expectations evolve, it is anticipated that the distinction between code-built and high-performance homes will diminish over the next decade.

Training and education remain top priorities. Appraisal panels must expand their expertise, and builders, contractors, and real estate professionals need ongoing support to stay current with advances in green building and valuation. The increasing adoption of standardized tools and certifications will further facilitate accurate valuation and financing.

Conclusion

The transition to high-performance, green homes offers immense benefits in terms of operational costs, comfort, resilience, and long-term value. However, realizing these benefits hinges on the ability of the housing industry to align financing, appraisal, and educational practices with the realities of modern construction and market demand. By embracing integrated funding strategies, leveraging certifications, and prioritizing data transparency and professional training, the industry can bridge the remaining gaps and ensure that sustainable housing reaches its full potential for all stakeholders.

Key Takeaways

  • Accurate valuation of green homes depends on robust data, third-party certification, and appraiser competency.
  • Building codes are increasingly aligning with green building standards, making high performance the new normal in many regions.
  • Financing tools—from rebates and incentives to innovative mortgage products—are evolving to support high-performance construction and retrofits.
  • The retrofit market represents a significant opportunity for energy savings and property value enhancement, especially in older homes.
  • Resilience, multi-generational living, and integrated technologies (such as ADUs and solar) are shaping the future of residential design.
  • Comprehensive documentation and clear communication by real estate professionals are critical for maintaining the value of high-performance features during resale.
  • Ongoing education and training for builders, appraisers, and lenders are essential to closing knowledge gaps and ensuring widespread adoption of sustainable building practices.
*Content created by a human speaker, transcribed by Zoom, and arranged by an AI LLM
Categories
Q&A Webinar After

Duct Diagnostics: Evaluation & Troubleshooting for Real-World Systems

Brynn Cooksey Sr., the Air Doctr, joined us recently for our  Weekly Wednesday Free CEU webinar Series.

If you missed this session, want to rewatch it, or want to share it with a friend or colleague, you can now do so, as the recording, an extra Q&A follow-up, and an article on the topic are available below. 

What the session was about, according to our live attendees

The webinar provided attendees with valuable insights into diagnosing and optimizing ducted HVAC systems, emphasizing the importance of understanding static pressure, airflow, and duct leakage. Participants learned about a variety of diagnostic tests and tools—such as pressure pans, duct blasters, and manometers—for identifying issues that affect system performance, comfort, and energy efficiency. Key takeaways included the need for proper duct sealing and sizing, the limitations of common materials like duct tape, and the significant impact of pressure imbalances and leaks. Both newcomers and seasoned professionals gained practical tips and a greater appreciation for thorough, methodical testing and maintenance of ductwork to ensure optimal system operation.

Please help us keep these webinars and writings going by becoming a supporting GHI member or by making a donation. 

Article Based on Webinar*

Abstract

Effective ductwork is at the heart of energy-efficient, healthy, and comfortable homes. As the residential sector increasingly adopts advanced HVAC systems—particularly air source heat pumps—duct system performance has become even more critical for both new and existing homes. This article synthesizes expert insights and field experience on duct diagnostics, evaluation, and practical improvements. The focus is to empower housing professionals, builders, and contractors to understand, assess, and optimize duct systems for better comfort, durability, and sustainability. Drawing exclusively on material from a GreenHome Institute educational session, this white paper covers core concepts, diagnostic methods, common problems, and actionable solutions for robust duct design and troubleshooting.

Introduction

The duct systems installed in residential buildings are fundamental to the success or failure of heating, cooling, and ventilation strategies. From single-family homes to multifamily dwellings, the quality of ductwork directly impacts energy consumption, indoor air quality, comfort, and the longevity of mechanical equipment. As heat pump technology and decarbonization efforts accelerate, scrutiny of duct systems—many of which were poorly designed, undersized, or inadequately sealed—has never been more urgent. Even in new construction, suboptimal ductwork remains a persistent problem, often resulting in discomfort, inefficiency, and system failures.

This article will explore the technical principles of duct system evaluation, highlight best practices for diagnostics and balancing, and offer solutions for common issues encountered in the field. While the content is aimed at housing professionals, the technical material is presented in an accessible manner for a broad audience, including contractors, builders, and interested homeowners.

The Role and Purpose of Duct Systems

A properly designed duct system delivers conditioned air efficiently and evenly throughout every room in a home. According to established standards, a well-designed system should keep room temperature variations within three degrees Fahrenheit. This evenness is essential for occupant comfort and energy efficiency.

Ducts must not only be sized appropriately but also be tightly sealed and balanced for both supply and return air. Any deficiencies in these areas can lead to a cascade of issues: uneven temperatures, noisy operation, excessive energy consumption, and even safety hazards such as heat exchanger failures and indoor air quality problems.

Sizing and Balancing: The Foundation of Performance

Field surveys of nearly 4,000 homes—ranging from early 1900s houses to those completed as recently as 2020—have revealed a staggering reality: nearly 99% of duct systems are undersized, often operating at half the required capacity. This is not merely a legacy problem. Many new homes, despite using advanced heating and cooling equipment, are delivered with duct systems that fail to meet even the minimum design criteria.

Proper sizing starts with accurate load calculations (Manual J) and duct design procedures (Manual D). The goal is to ensure every room receives the calculated cubic feet per minute (CFM) of air needed for both heating and cooling loads. When the system is not balanced—meaning the supply and return airflows do not match—comfort, efficiency, and equipment reliability all suffer.

Balancing is a commissioning process involving the measurement and adjustment of airflow at each register, typically using devices such as a flow hood. Balancing dampers—metal blades installed inside ducts—allow fine-tuning of airflow to different branches, compensating for differences in heating and cooling requirements. However, balancing is rarely performed in residential construction, often resulting in persistent comfort complaints and inefficient operation.

Duct Sealing and Insulation: Controlling Energy Loss

Duct leakage is a major source of energy waste in both old and new homes. Studies indicate that unsealed ductwork can lose 20% to 40% of conditioned air, with an average of about 30%. Sealing is essential but must be preceded by proper sizing—sealing undersized ducts can worsen static pressure and damage equipment.

Ducts running through unconditioned spaces (such as vented attics or crawl spaces) require both sealing and insulation. Uninsulated ducts in these locations lead to heat loss or gain, reducing system capacity and increasing heating or cooling loads. Inside the thermal boundary of the home, insulation is less critical but may still improve comfort.

System Controls and Advanced Solutions

Modern thermostats have evolved into sophisticated building controls, offering features like geofencing and remote access. These advancements enable more precise temperature management and can help optimize system performance. Additionally, zoning—using motorized dampers and multiple thermostats—can address persistent comfort issues in multi-story or large homes, yielding up to 10% energy savings when implemented with proper duct sizing.

Consequences of Poor Duct Design and Installation

Inadequate duct systems manifest in a variety of problems:

  • Hot or cold spots in rooms, making them uncomfortable or unusable
  • Longer running times for HVAC equipment, driving up utility bills
  • Equipment short cycling, leading to premature failure of components such as compressors or heat exchangers
  • Safety hazards, including cracked heat exchangers (which can release combustion gases into living spaces)
  • Excessive system noise, which can degrade quality of life
  • Indoor air quality concerns, especially when return leaks pull in attic or crawl space air containing dust, mold, or other contaminants

Diagnostic Methods: Evaluating Duct System Performance

Thorough evaluation of duct systems requires a systematic approach, combining client interviews, physical inspection, and a suite of diagnostic tests. Key techniques include:

  1. Pressure Pan Test: Measures pressure differences at registers with a blower door running. Detects leaks connecting the duct system to outside the building shell.
  2. Duct Leakage Test (Duct Blaster): Quantifies total duct leakage by pressurizing or depressurizing the duct system to 25 pascals and measuring airflow loss. Leakage should not exceed 10% of total system airflow.
  3. Room-to-Room Pressure Differential: Assesses pressure imbalances between rooms with doors closed, using a manometer. Imbalances greater than 3 pascals indicate inadequate supply or return paths, leading to comfort and efficiency problems.
  4. Direct Airflow Measurement: Using flow hoods or vane anemometers, technicians measure delivered CFM at each supply and return register, comparing actual values to design targets.
  5. Static Pressure Measurement: External static pressure readings (before and after filters and coils) provide a proxy for airflow. High static pressure indicates restrictions—often due to undersized ducts, dirty filters, or excessive bends.
  6. Temperature Rise Test: For combustion appliances, measuring the temperature difference across the heat exchanger can indicate insufficient airflow if the rise exceeds manufacturer specifications.
  7. Duct Traverse and Other Tools: Advanced tools such as flow plates and duct traverses (using multiple velocity measurements) offer high accuracy for airflow quantification, though they may be more time-consuming.

Common Problems and Practical Solutions

  • Duct Leakage: The most energy- and comfort-robbing issue. Sealing with mastic or approved sealants (not “duct tape”) is essential. Prioritize ducts outside the thermal envelope for sealing and insulation.
  • Undersized Ducts: If airflow measurements fall below calculated needs and static pressure is high, ducts may need to be enlarged or additional supplies/returns added.
  • Imbalanced Airflow: Use balancing dampers, jumper ducts, transfer grilles, or dedicated returns to address pressure differentials between rooms.
  • Noise: Excessive noise typically results from high static pressure or poor duct design. Reducing restrictions and increasing duct size are effective remedies.
  • Filter Upgrades: High MERV filters improve air quality but can increase static pressure. Always verify that the system can accommodate higher resistance filters before upgrading.
  • Return Path Limitations: Inadequate return air is a common culprit for pressure imbalances. Solutions include undercutting doors (with some loss of privacy), installing jumper ducts or transfer grilles, or adding dedicated returns.
  • Zoning Adjustments: For large or multi-story homes, zoning with motorized dampers and multiple thermostats can correct persistent comfort problems and save energy.

Assessment and Remediation Process

A comprehensive evaluation should begin with a client interview to identify comfort complaints, noise issues, or specific rooms that are problematic. This is followed by a physical inspection for visible flaws—such as disconnected ducts, improper modifications (e.g., “Bluetooth ducting” where other trades have compromised the ductwork), or signs of leakage.

The six major diagnostic tests outlined above provide quantitative data to confirm or refute suspected issues. Once identified, solutions can be targeted—from simple sealing and balancing to more involved duct modifications or equipment replacement.

Special Considerations for Existing and New Homes

Older homes often present hidden challenges—ducts buried in wall cavities, pan joists serving as return pathways, or inaccessible duct runs. While it may not always be feasible to replace or enlarge ducts without major renovations, targeted improvements (such as adding returns, sealing accessible joints, or employing advanced diagnostics like borescopes) can still yield significant benefits.

For new construction, engaging duct design professionals early in the process is essential. This ensures that load calculations, duct sizing, and layout are coordinated with architectural and structural plans. Duct leakage and performance testing should be included at mid-construction to enable corrections before finishes are installed.

The Cost of Inaction

While professional duct evaluation and remediation entail upfront costs, the price of neglect is far higher: persistent comfort issues, inflated utility bills, compromised indoor air quality, and premature equipment failure. Investing in proper design, testing, and commissioning pays dividends over the life of the home.

Key Takeaways

  • Duct systems play a critical role in home energy efficiency, comfort, and indoor air quality.
  • A vast majority of residential duct systems—both old and new—are undersized and/or poorly sealed.
  • Proper duct system performance requires accurate load calculations, professional design, and thorough commissioning.
  • Diagnostic tests such as pressure pan, duct leakage, static pressure, and direct airflow measurements are essential tools for identifying and solving duct problems.
  • Sealing ducts is important but must follow correct sizing; insulation is crucial for ducts outside the building’s conditioned envelope.
  • Balancing airflow with dampers and considering zoning can solve persistent comfort issues, especially in larger or multi-story homes.
  • System noise, pressure imbalances, and temperature variations are often symptoms of underlying duct design or installation faults.
  • High-performance filters should be matched with duct system capacity to avoid excessive static pressure.
  • Early involvement of qualified professionals in both new construction and retrofit projects is key to achieving high-performance duct systems.
Addtional Q&A Answers
Q: On the general static pressure and fan speed chart, was that a real chart? It looked like the equipment would have to have been rated at 0.3 IWC? So if it’s even 0.5 IWC it would be too much pressure?
A: This was an example to demonstrate how to use the chart for Total External Static Pressure (TESP). The chart was not specific to a particular piece of equipment but rather intended as a general reference.
Q: Brett, will this duct handout be shared via link in Zoom chat or emailed to us separately?
A: We are having issues with the handout at the moment. Please stay tuned for updates.
Q: How about internal video inspection?
A: (Answered live) We take a sample of the duct system to inspect for cleanliness.
Q: This info is very technical for an architect to explain to a client who has problems with an existing or new system that would need to check duct-leaks & balance a 2-season system. If I am to recommend a verification process, what would be the cost a client would need to pay for a 2,000 SF 2-storey with basement house that covers both seasons? (This would be the starting point)
A: Hi Rosmal, the cost depends on several factors. Proper duct leakage testing requires knowing the square footage served by each system. For duct balancing, it’s recommended to have mechanical plans and manufacturer specs to compare with the original HVAC design. The total cost will likely exceed $1,000.
Q: Without removing walls and rebuilding ductwork from scratch, how do you go about balancing and getting cool air to the second floor? It’s at least 10 degrees warmer or colder upstairs.
A: Sarah, I recommend starting with duct leakage testing to ensure the ducts aren’t excessively leaky. Poorly installed insulation can also contribute to large comfort issues, which I often see as an energy auditor. Zoning is the only true way to resolve a hot second floor, as the thermostat will satisfy the first floor long before the second floor is cooled.
Q: How is a pan between joists replaced? Is it simply by installing a complete rectangular duct between joists?
A: (Answered live) Replace the pan joist return air with rectangular or round ductwork as much as possible. Note that static pressure may still be high due to the tightness of wall cavities.
Q: If replacing ducts at time of renovation, exposed ducts vs. boxed in? Is exposed ducting (not insulated) in living space an advantage due to more radiation surface in addition to conditioning via air flow?
A: (Answered live) The radiant heat is lost to the inside of the building shell. There is generally no benefit to boxing in ducts, and it is not cost effective.
Q: I was referring to ducts inside the living space, not external to living space.
A: The duct loss isn’t always where you want it; it may help if the loss is to the room being conditioned, but not if it goes elsewhere. This is another reason why minisplits or window units are often a good solution.
Q: Drew, as a Rater I think mini splits are awesome, especially ductless ones. However, installing them on large custom homes—which is a bulk of our new builds out here—is not very doable and would require a lot of outdoor units.
A: That’s correct. While ductless mini splits are excellent for certain applications, large custom homes may face practical limitations with the required number of outdoor units.

Please help us keep these webinars and writings going by becoming a supporting GHI member or by making a donation. 

*Content created by a human speaker, transcribed by Zoom, and arranged by an AI LLM
Categories
Uncategorized

The Rise of Indoor Air Monitoring in Homes and Mixed-Use Buildings

To meet evolving environmental standards and modern remote work demands, many building owners and property managers are placing increased focus on indoor air quality.

Data suggests the average person spends as much as 90% of their time indoors, where the airtight nature of modern, energy-efficient buildings can cause issues with indoor air pollution.

In modern buildings, indoor air can be 2-5 times more polluted than outdoor air, posing a risk to public health and the potential to drive economic loss. In an effort to address these issues, more focus is being placed on indoor air quality monitoring in homes and mixed-use buildings.

Why Indoor Air Monitoring Matters in Modern Buildings

Rising levels of pollution in urban environments and the airtight nature of modern construction are combining to cause issues with hazardous indoor air quality. Measures intended to reduce energy loss can trap pollutants brought in through ventilation systems and generated through activities like cooking and cleaning inside modern buildings, worsening air quality for residents.

At present, as many as 41% of global cities suffer from air pollution more than 7 times higher than the World Health Organization’s (WHO) safe limits. When this polluted air is brought into buildings unnoticed, it can cause serious health issues and worsen inhabitants’ quality of life.

The negative impacts of poor indoor air quality include:

  • Sick building syndrome: Poor indoor air quality can cause building-related illnesses like fatigue and headaches, affecting 30% of workers in new and renovated buildings.
  • Economic loss: Poor indoor air quality is estimated to cost the U.S. economy $168 billion a year in lost productivity due to workers suffering from sick building syndrome.
  • Premature death: WHO data suggests 3.2 million people globally die prematurely in an average year as a result of diseases caused by unaddressed indoor air pollution.

Improving Indoor Air Quality in Homes and Mixed-Use Buildings

In an effort to address worsening indoor air quality, many property owners and managers are exploring novel ways to detect and minimize indoor air pollution. By leveraging smart devices to continuously monitor air quality and identify sources of pollution, operators can address the unique challenges facing their facilities and adjust wider systems to improve indoor air quality.

Identifying Pollutant Sources

Internet of Things (IoT) sensors installed around homes and mixed-use buildings are used to continuously monitor air quality for signs of common pollutants. Modern multi-sensor devices can accurately detect specific contaminants like CO2, VOCs and e-cigarette vapor, as well as provide live indoor air quality index readings, to help building operators tackle issues promptly.

Teams can be sent live alerts and view index readings from a remote-accessible management platform. This process supports wide-ranging applications, e.g. devices can be used as vape sensors in schools, hotels and offices, pollutant detectors in manufacturing facilities and air quality index trackers in apartments, offering operators real-time visibility into air quality issues.

Enacting Automated Responses

Through intelligent integrations, IoT sensor data can be used to trigger real-time reactions to indoor air quality issues. Operators can choose to link IoT sensors to existing infrastructure like ventilation, filtration and humidity control systems to power automated incident responses.

Unique thresholds can be set within the system to maintain safe air quality in unique spaces. In practice, this enables operators to not only engage HVAC systems in response to air quality issues, but also receive alerts and trigger unique responses to site-specific issues, e.g. vaping triggers cameras to record, moisture triggers dehumidifiers or VOCs trigger local exhaust fans.

Pursuing Continuous Improvements

Alongside helping to address indoor air quality issues in real-time, intelligent sensor systems provide operators with high-quality insights into environmental conditions over time. This data can be used to generate site-specific reports that detail pollutant levels across the property at specific times to help operators better understand the root cause of different air quality issues.

Report findings can be used to inform continuous improvements to organizational practices. For example, if VOCs are found to spike shortly after a room has been cleaned, operators can use this data to adjust cleaning schedules and turnaround times for allowing residents back in.

Creating Safer Indoor Environments for Modern Communities

As urban air pollution worsens, the importance of indoor air quality monitoring continues to rise. By deploying smart solutions to detect, address and report on air quality issues, building owners and operators can help to create safer indoor environments for modern communities.

Author: SEENE